This application claims the priority of German Patent Document No. 10133919.4, filed Jul. 12, 2001, the disclosure of which is expressly incorporated by reference herein.
The invention relates to an electromechanical transmission for motor vehicles.
Automatic transmissions, in which gear changes occur automatically without the involvement of the driver, are used to increase driving comfort. The disadvantages of automatic transmissions are the high manufacturing costs, weight and design volume. A more cost-effective variation of the currently common automatic transmissions is automated changeover gears. However, automated change over gears have the disadvantage that, during the shifting process, the tractive power (the power delivered to the drive wheels) is interrupted. An alternative that has no tractive power interruptions is double-clutch transmissions with two separate countershafts. The disadvantage here is the greater mechanical and thermal strain on the clutches as well as complex control for a jolt-free shifting process.
The object of the invention is to create a transmission for motor vehicles, which has an automatic shifting process without interruption of the tractive power and allows for a broad spectrum of different shifting strategies.
An electromechanical transmission that meets these requirements is described hereinafter.
In an electromechanical transmission according to the invention, a controlled clutch between the internal combustion engine and the shifting transmission is not required. A shifting process can be performed without tractive power interruptions. The input shaft of a planetary gear is connected to the crankshaft of an internal combustion engine. The two output shafts of the planetary gear are connected to the two countershafts of a shifting transmission and to the two rotors of an electric drive, which can function as a motor or a generator. The two rotors can thus function as a conventional starter or a generator, and they are used to control the shifting processes of the connected shifting transmission parts. The electromechanical transmission according to the invention is of low weight and small size.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.